Introduction to Environmental Science

Chapter 6: Human Population and Urbanization

ARE THERE TOO MANY OF US?

CASE STUDY

6-1 How many people can the Earth support?

The human population has grown rapidly due to technology, improved medical techniques, emphasis on hygiene, and expansion of agriculture and industry.

Population growth has slowed but is troubling because we do not know how long we can continue without overshooting earth's carrying capacity for humans.

No population, including humans, can continue to grow indefinitely.

"We do not know how long we can continue increasing the earth’s carrying capacity for humans without seriously degrading the life-support system that keeps us and many other species alive. "

Natural Capital DegradationAltering Nature to Meet Our Needs

Reduction of biodiversity

Increasing use of the earth's net primary productivity

Increasing genetic resistance of pest species and disease-causing bacteria

Elimination of many natural predators

Introduction of potentially harmful species into communities

Using some renewable resources faster than they can be replenished

Interfering with the earth's chemical cycling and energy flow processes

Relying mostly on polluting and climate-changing fossil fuels

3 Factors of Human PopulationBirth: FertilityDeath: MortalityMigration: Emigration and Immigration

Population increases through births and immigration and decreases through deaths and emigration.

[Population change = (Births + Immigration) - (Deaths + Emigration)]

1. The crude birth rate is the number of live births per 1,000 people in a population in a specific year. 2. The crude death rate is the number of deaths per 1,000 people in a population in a specific year.

6-2 What Factors Influence the Size of the Human Population?

UN WORLD POPULATION PROJECTION BY 2050

Fertility is the number of births that occur to an individual woman or in a population.

1. The changing nature of fertility rates affect population growth.

a. Replacement-level fertility is the number of children needed to replace their parents.

b. Total fertility rate (TFR) is the average number of children that a woman has during her fertile years.

FERTILITY

Factors Influence Birth and Fertility Rate

1. More children work in developing countries; they are important to the labor force.

2. The economic cost of raising and educating children determines their numbers.

3. If there are available private/public pension systems, adults have fewer children because they don't need children to take care of them in old age.

4. People in urban areas usually have better access to family planning, so have fewer children.

5. If women have educational and economic choices, they tend to have fewer children.

6. When the infant mortality rate is low, people have fewer children.

7. The older the age at which women marry, the fewer children they bear.

8. If abortions are available and legal, women have fewer children.

9. The availability of reliable birth control allows women to space children and determines the number of children they bear.

Factors that have caused a decline in death rates are the following:

Factors that have caused a decline in death rates are the following:

1. Better food supplies and nutrition, and safer water supplies contribute to people living longer.

2. Advances in medicine and public health, and improved sanitation and personal hygiene also contribute to people living longer.

Measures of overall health

1. Life expectancy is the average number of years a newborn can expect to live.

2. Infant mortality rate is the number of babies out of every 1,000 born who die before their first birthday.

a. This rate reflects a country's level of nutrition and health care.b. It is the single best measure of a society's quality of life.3. U.S. infant mortality rate is higher than 40 other countries

because:a. Inadequate health care for poor women and for their babies.b. Drug addiction among pregnant women.c. High birth rate among teenagers.

Migration Historically, the United States has admitted more immigrants than all

other countries combined. Some 60% of the U.S. population supports limiting legal immigration. A recent study suggests that to maintain a viable workforce as baby boomers retire, the U.S. would have to absorb many more immigrants per year than it currently does. However, a reduction in immigration may help mediate the enormous environmental footprint the United States currently has.

THE U.S. POPULATION IS GROWING RAPIDLY

CASE STUDY

BIRTH RATE IN U.S. (1910-2008)

THE UNITED STATES: A NATION OF IMMIGRANTS

CASE STUDY

• Immigration – legal and illegal – 39% population growth

• 1820–1960: Most immigrants European

• Since 1960– Latin America – 53%– Asia – 25%– Europe – 14%

• Opponents of immigration

– Stabilize population sooner

– Reduce growing environmental impact

– 60% of population favor reducing immigration

• Proponents of immigration

– Important historical role

– Do menial jobs and pay taxes

– Add cultural vitality

– Replace retiring baby boomers

6-3 HOW DOES POPULATION'S AGE STRUCTURE AFFECT ITS GROWTH AND DECLINE?

GENERALIZED POPULATION AGE STRUCTURE DIAGRAMS

POPULATION AGE STRUTURE BY AGE AND SEX IN DEVELOPED AND DEVELOPING COUNTRIES

TRACKING THE BABY-BOOM GENERATION IN THE UNITED STATES

Some Problems with Rapid Population Decline

Can threaten economic growth

Labor shortages

Less government revenues with fewer workers

Less entrepreneurship and new business formation

Less likelihood for new technology development

Increasing public deficits to fund higher pension and health-care costsPensions may be cut and retirement age increased

RISING DEATH RATE: THE AIDS TRAGEDY

●25 million killed by 2008

●Many young adults die: loss of most productive workers

●Sharp drop in life expectancy

●International community called upon to- Reduce the spread of HIV through education and

health care- Financial assistance and volunteers

6-4 HOW CAN WE SLOW HUMAN POPULATION

●Demographic transition stages - Preindustrial- Transitional

● May lead to a demographic trap- Industrial- Postindustrial

FAMILY PLANNING

1. Information is given on birth spacing, birth control, and health care.

2. Family planning has been responsible for at least 55% of the drop in TFRs in developing countries.

3. Family planning has also reduced both legal and illegal abortions per year.

4. Services come through educational and clinical services.

1. Almost one-half of pregnancies in developing countries are unplanned and 26% end in abortion.

2. Women want to limit their pregnancies but have no access to contraceptives.

5. Empowering women by providing education, paying jobs, and support for their human rights can slow population growth.

1. Women work two-thirds of all the hours worked, but receive 10% of the world’s income.

SLOWING POPULATION GROWTH IN CHINA

CASE STUDY

POPULATION GROWTH IN CHINA

●One-child families●Halved birth rate and drastically reduce TFR●Improved quality of life●Strict family planning●Sons still preferred – gender imbalance

POPULATION GROWTH IN CHINA

●Population rapidly aging

●Rapidly growing economy

●Larger middle class increases resource consumption and waste

●Sustainable economic plan needed to avoid environmental degradation

SLOWING POPULATION GROWTH IN INDIA

CASE STUDY

POPULATION GROWTH IN INDIA

●Tried to slow population growth for five decades

●Most populous country in 2015●Population Control: Gender bias●Problems increase with growing population

- Poverty- Malnutrition- Environmental degradation- Growing middle class – resource consumption

6-5 WHAT ARE THE MAJOR URBAN RESOURCE AND ENVIRONMENTAL PROBLEM

URBAN LIVING- Half the world lives in urban areas- 79% of Americans live in cities- 50% of world population lives in cities- Urban areas continue to grow

● Natural increase● Immigration

Major Trends in Urban Growth• Proportion of urban global population growing• Number and sizes of urban areas mushrooming• Rapid increase in urban populations in developing countries• Urban growth slower in developed nations• Poverty increasing

URBANIZATION IN UNITED STATES

CASE STUDY

URBANIZATION IN UNITED STATES

●1800–2009: urban population increased from 5% to 79%

●Migration patterns- Rural areas to large cities- Large cities to suburbs and smaller cities- Cities and suburbs to rural areas- North and East to South and West

●Better working and housing conditions compared to the past

● Improved environmental conditions●Problems in urban areas

- Aging infrastructure - Budget problems

URBAN SPRAWL CAUSES

●Prosperity

●Ample and affordable land

●Automobiles

●Cheap gasoline

●Poor urban planning

URBAN SPRAWL PROBLEMS

●Increased automobile use

●Decreased energy efficiency

●Destruction of cropland, forests, wetlands

●Economic deaths of some cities

1973 2003

Urban sprawl in and around the U.S. city of Las Vegas, Nevada, between 1973 and 2003.

Natural Capital Degradation

Urban Sprawl

Economic EffectsLand andBiodiversity

Water Energy, Air,and Climate

Loss of cropland

Loss of forests andgrasslands

Loss of wetlands

Loss andfragmentation ofwildlife habitats

Increased use of surfacewater and groundwater

Increased runoff andflooding

Increased surface waterand groundwaterpollution

Decreased naturalsewage treatment

Increased energy useand waste

Increased air pollution

Increased greenhousegas emissions

Can enhance climatechange

Decline ofdowntown businessdistricts

Increasedunemployment incentral city

Loss of tax base incentral city

ADVANTAGES OF URBANIZATION

●Economic development●Innovation●Education and jobs●Technological advances●Longer life spans●Better social and medical services●Recycling more feasible●Biodiversity increased●Increased energy efficiency

DISADVANTAGES OF URBANIZATION

●Unsustainable systems ●Lack of vegetation●Water problems ●Pollution and health problems●Noise pollution●Climate and artificial light●Urban heat islands●Light pollution

Inputs Outputs

Information

Energy

Food

Water

Rawmaterials

Manufacturedgoods

Money

Solid wastes

Waste heat

Air pollutantsWater pollutantsGreenhouse gasesManufactured goods

Noise

Wealth

Ideas

MEXICO CITYCASE STUDY

MEXICO CITY

●Large population●Severe noise, water, and air pollution●50% unemployment●100,000 premature deaths per year●3 million without sewer●Fecal snow●Geography contributes to air pollution●Progress – tree planting and lower air pollution

6-6 HOW DOES TRANSPORTATION AFFECT URBAN ENVIRONMENTAL IMPACT

●Concept 6-6 In some countries, most people live in dispersed urban areas and depend mostly on motor vehicles for their transportation.

Cities Can Grow Outward or Upward

●Compact cities- Transportation by walking, biking, or mass

transit● Hong Kong, Tokyo

●Dispersed cities- Transportation by automobile

● Most American cities

Trade-Offs

Bicycles

Advantages Disadvantages

Require littleparking space

Secure bike parkingnot yet widespread

Burn no fossilfuels

Are impractical forlong trips

Take fewresources tomake

Provide no protectionfrom bad weather

Are quiet andnon-polluting

Provide littleprotection in anaccident

Advantages

Trade-Offs

Mass Transit Rail

Disadvantages

Is expensive to buildand maintain

Is cost-effective onlyin densely populatedareas

Commits riders totransportationschedules

Can cause noise andvibration for nearbyresidents

Reduces carcongestion incities

Causes fewerinjuries anddeaths thancars do

Reduced need formore roads andparking areas

Uses less energyand produces lessair pollution thancars do

Trade-Offs

Is costly to run andmaintain

Causes noise andvibration for nearbyresidents

Has some risk ofcollision at carcrossings

Is much more energyefficient per rider than carsand planes are

Produces less pollutionthan do cars and planes

Can reduce need for moreair travel, cars, roads, andparking areas

Advantages Disadvantages

Rapid Rail

Trade-Offs

Can lose money becausethey require affordable fares

Can get caught in trafficand add to noise andpollution

Commit riders totransportation schedules

Can greatly reduce caruse and air pollution

Can be rerouted asneeded

Cost less to developand maintain thanheavy-rail system

Advantages Disadvantages

Buses

Environmentally Sustainable Cities

●Smart growth●Eco cities

- Use renewable energy as much as possible- Build and design people-oriented cities- Use energy and matter efficiently- Prevent pollution and reduce waste- Recycle, reuse, and compost - Protect and encourage biodiversity- Promote urban gardens and farmers markets- Zone for environmentally stable population

levels

Smart Growth ToolsLimits and Regulations

Limit building permitsUrban growthboundaries

Greenbelts around cities

Public review of newdevelopment

Zoning

Encourage mixed use ofhousing and smallbusinessesConcentratedevelopment along masstransportation routes

Promote high-densitycluster housingdevelopments

Planning

Ecological land-useplanning

Environmental impactanalysisIntegrated regionalplanningState and nationalplanning

Protection

Preserve existing open space

Buy new open space

Buy development rights thatprohibit certain types ofdevelopment on land parcels

Taxes

Tax land, not buildings

Tax land on value of actual use(such as forest and agriculture)instead of on highest value asdeveloped land

Tax Breaks

For owners agreeing not to allow certain types of development (conservation easements)For cleaning up and developing abandoned urban sites (brownfields)

Revitalization and New GrowthRevitalize existing towns and citiesBuild well-planned new towns and villages within cities

Solutions

THE ECOCITY CONCEPT IN CURITIBA, BRAZIL

CASE STUDY

CURITIBA, BRAZIL

●CURITIBA -“ecological capital” of Brazil●Inexpensive, efficient mass transit●High-rise apartments near bus routes, mixed-use

structures ●Bike and pedestrian paths●1.5 million trees planted ●Recycling●Many services for the poor●Emphasis on ecological awareness, health,

literacy

END OF CHAPTER 6